Internal-combustion engine of the tandem type.



\ T. RIGBY.

INTERNAL COMBUSTION ENGINE OF THE TANDEM TYPE. APPLIOATION FILED 00T.16, 1911.

1,018,372. Patented Feb. 20, 1912.

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Inventor." Thomas Big In COLUMBIA PLANbnRAPl-l cc, WASHINGTON, n. c.

THOMAS RIGBY, 0F DUMFRIES, SCOTLAND.-

INTERNAL-COMBUSTION ENGINE OF THE TANDEM TYPE.

Specification of Letters Patent.

Patented Feb. 20, 1912.

Application filed October 16, 1911. Serial No. 654,943.

To all whom 'it may concern:

Be it known that I, THoMAs RIGBY, a subject of the King of Great Britain'and Ireland, and a resident of Station Hotel, Dumfries, Scotland, have invented certam new and useful Improvements in Internal-Oombustion Engines of the Tandem Type, of which the following is a specification.

This invention relates to improvements in internal combustion engines of the tandem type, and particularly to the tandem vertical type working on the singleacting Otto cycle, and the invention consists 1n supplying in such engines a supplemental charge of gas, air, or gaseous combustible mixture under pressure to the power cylinder over and above the ordinary charge drawn into the cylinder by suction (or otherwise supplied in the ordinary way), the said supplemental quantity being admitted in accordance with the requirements of the load, but preferably only being brought into operation to meet an overload.

In an Otto cycle gas engine the weight of the charge taken in during the suction stroke defines the limit of power of the engine; but in this invention, gaseous fluid is admitted separately to the engine cylinder at or near the end of the suction stroke and before the compression stroke is sufliciently advanced to prevent it entering. The effect of this is to put the previously drawn in main charge under a certain degree of compression, according to the amount of supplemental gaseous fluid admitted, to the working cylinder.

Tandem vertical engines are usually constructed in such a manner that the space between the upper piston and the top of the lower cylinder is practically closed, with the result that as the pistons are descending, the compression of the elastic fluid contained therein usually has the effect of a cushion retarding the weight of the falling pistons. In this invention, this cushion is dispensed with when required, and the displacement of the bottom side of the upper piston is used for the purpose of forcing the supplemental gaseous fluid into the working cylinder. In an engine of the tandem type working on the single acting Otto cycle, there is an explosion once every revolution, and, as the upper piston descends once every revolution, the displacement of the upper piston can be used in order to pump the supplemental gaseous fluid, alternately, once every revolution, to each cylinder. If desired, the displacement of the bottom side of the upper piston may be used to deliver the supplemental gaseous fluid, at all loads, to the working cylinder, but generally when possible it is preferable not to add any supplemental fluid to the working charge when working below the normal full load of the engine, as thereby the best and most economical result is ob tained.

The supplementary gaseous fluid is admitted to the working cylinder by means of any suitable valve mechanism which will graduate the amount of supplemental gaseous fluid added to the ordinary working charge so as to increase the available mean pressure in the cylinder.

If desired, the additional gaseous fluid may be cooled before admission to the working cylinder to a temperature below that of the charge drawn in by suction on the charging stroke, preferably to a temperature nearly as low as that of the atmosphere.

It will be understood that the clearance space between the bottom side of the upper piston and the cover of the lower cylinder can be of such a dimension that there can be admitted supplemental gaseous fluid to the working charge to the extent of fifty per cent. to sixty per cent. or even a higher percentage.

In the accompanying drawing which is a vertical sectional elevation of a vertical tandem internal combustion engine working on the single acting Otto cycle, aand b are the working cylinders arranged tandem, the two pistons being designated 0, c, and mounted upon a common piston rod (Z. The rod 39 connects the pistons to the crank shaft (not shown), while the compression space is formed by closing in the end of the cylinder a, the compression space being designated a. The ordinary admission valves of the engine are designated 6, e, and the exhaust valves f'of the two working cylinders. The side shaft 9 has two cams q thereon, which operate through connecting rods I0 and links the valves is and is, arranged always to open at a constant time and to a definite extent, whether any supplemental charge is admitted to the working cylinder or not. The cam shaft 9 also has a cam g thereon, arranged to operate the exhaust valves f. The ordinary admission valves e, e, are similarly actuated by a second cam,

not shown, but also on the cam shaft g. The valve y, as shown, is a back-pressure valve, which opens automatically during the admission of supplemental charge, and during the up stroke of the upper piston, but which closes automatically on the return stroke. The valve 02, as shown, is also an automatic non-return valve, which opens auto1natically when supplemental charge is being delivered into the receiver 2'.

The receiver in cases where cooling of the additional charge is employed may be fitted with means for increasing the cooling surface, such as tubes, 1, through which the gaseous fluid passes, these tubes passing through chamber, 2, through which water is circulated by means of pipes i and 71 The pipe it conveys the supplemental gaseous fluid to the receiver 2', while the pipes j and y" connect the receiver '5 to the mechanically operated valves 70 and k. The pipes m and m are the connections to the valve chamber containing the regulating valve n, which is operated from the governor (not shown) by a rod n, and these pipes are arranged so that if a mixture of gas and air is being passed as a supplemental charge, the gas and the air are separated right up to the valve box.

The quantity of supplemental charge admitted to each working cylinder is con-' trolled according to the variations in overload by restrictlng the amount of gaseous fluid admitted to the clearance space a between the bottom side of the upper piston c and the top of the lower cylinder Z) during the suction stroke into this clearance space. As a consequence, if the valve 02, is closed altogether by the governor when working at loads below the normal, there is no gase ous fluid at all admitted into the clearance space a. As soon, however, as the normal load is exceeded, the action of the governor connection rod n is to open the admission valve n to correspond with the amount of extra gaseous fluid required, with the result that on the delivery stroke an amount corresponding to the opening of this valve n is delivered through one of the valves is or 70 (whichever is due to open), and in consequence, a supplemental charge is admitted atthe end of the ordinary working stroke.

Although this invention is mainly intend.- ed for the vertical tandem type of internal combustion engine, it will be seen that if the cylinders are arranged tandem, either horizontally or at any other angle to the vertical the same results can be obtained with little or no modification of the mechanism.

Having thus described my invention what I claim is 1. In an internal combustion engine comprising working cylinders in tandem, a piston in each cylinder, a rigid connect-ion between the pistons, a compression chamber being formed at the inner end of the outermost cylinder, means for admitting combustible fluid to said cylinders, means for admitting a supplementary charge of combustible fluid to the said compression chamber, means for conducting the charge from the said chamber in alternation to the working cylinders, and means adapted to be controlled from a governor for controlling the admission of the supplementary charge to the engine,

2. In an internal combustion engine comprising working cylinders in tandem, a piston in each cylinder, a rigid connection between the pistons, a compression chamber being formed at the inner end of the outermost cylinder, means for admitting combustible fluid to the cylinders, a receiver adjacent to the cylinders, means adapted to be operated by an engine governor for admitting a supplementary charge of combustible fluid to the compression chamber in accordance with the load on the engine, means for conducting the said charge from the compression chamber to the receiver, and means for conducting the supplementary charges in alternation to the working cylinders of the engine from the receiver.

3. I11 an internal combustion engine comprising working cylinders in tandem, a piston in each cylinder, a rigid connection between the pistons, a compression chamber being formed at the inner end of the outermost cylinder, a receiver adjacent to the cylinders, a passage leading from the compression chamber to the receiver, a check valve in the passage, a passage from the receiver to each of the working chambers of the engine, valves for controlling the said passages, means operated by the engine for positively and alternately opening the said valves, means for admitting a supplementary charge to the compression chamber, said means having independent passages for the fuel and the air.

In testimony whereof I have signed my name to this specification in the presence of two subscribing witnesses.

THOMAS RIGBY. Witnesses:

BERTRAM I-I. MATTHEWS, H. D. JAMnsoN.

Copies of this patent may be obtained for five cents each, by addressing the Commissioner of Patents,

Washington, D. C. 

